Field of the Invention
The invention relates to a method of producing a smart card module, a smart card module produced by the method, and a combination smart card containing the smart card module.
A combination smart card (or combination card, for short) is to be understood below as a smart card in which data and information can be exchanged with a card read/write unit both in a conventional way by tapping electric contacts and in an inductive way without contacts.
Such combination cards can be used, for example, as a small change purse or for monitoring personal access with attendant means of registration.
For the purpose of conventional data transmission, smart cards have exposed contacts on a card surface which usually correspond to the ISO Standard 7810 or 7816 and which are read by means of electric lifting contacts. The contact surfaces for conventional data transmission are denoted below in general as first contact plane or, in a simplified fashion, as ISO contact surfaces. A chip module for such a conventional smart card is described, for example in German patent application DE A 39 24 439.
For the purpose of data transmission in an inductive way, an antenna is integrated into the smart card. Usually, an electric coil is arranged in the smart card body such that it cannot be seen from the outside. Coils with a carrier frequency in an open industrial band, for example 13.56 MHz, are suitably used in this context.
The invention is described below with reference to the example of an electric coil, but without being limited to that special implementation of an antenna. The smart card (SC) module produced by using the method according to the invention is, moreover, also basically suitable for making contact with other elements of a smart card with which contact is to be made.
If the two data transmission systems described above are to be combined in a smart card, it is necessary to create electrically conductive connections from the semiconductor chip both to the ISO contacts and to the coil.
The ISO contacts are produced, as a rule, in such a way that firstly a smart card module is produced which is then inserted (implanted) in a cutout in the card substrate. The smart card module comprises a flexible substrate material, for example a glass fiber reinforced epoxy film on one side of which the semiconductor chip is disposed, and on the other side of which the ISO contact surfaces are formed. The latter generally comprise a copper layer with a surface finish comprising a nickel layer and a gold layer. The ISO contact surfaces and the semiconductor chip are connected in a conducting fashion to bond wires through cutouts in the module substrate film.
It would be conceivable in theory for the contacts required to make electrical contact with the coil to be placed on the ISO contact surfaces, that is to say to widen the ISO contact surfaces by two additional fields.
However, such an arrangement would have the disadvantage that the connecting sites would come to lie on the surface of the smart card and be susceptible thereby to interference effects and tampering. For example, shifts in the natural frequency can result from the contact surfaces and/or physical contacts touching metal objects and short circuits thereby triggered. The result would be malfunctions or complete functional failure. In order to exclude such disturbances to and tampering of the information to be transmitted inductively, there was therefore a need to find other ways of making contact between the semiconductor chip and the coil.
German patent application DE A 195 00 925 describes a smart card for both contactless and conventional data transmission. There, the chip module incorporated in the card body has two mutually opposite connecting planes for conventional data exchange and/or for connecting an antenna.
Moreover, DE A 195 00 925 describes methods which can be used to incorporate such a chip module in the card body and form the required contacts.
The methods used to date for producing smart card modules include numerous process steps such as, for example, the separate structuring of one or more connecting planes (for example by etching) and/or of the module substrate ribbon (by punching or drilling) and are therefore time-consuming and expensive.